A male sa'angreal made during the War of the Shadow at the end of the Age of Legends. It is in the shape of a crystal sword, and like all sa'angreal, glows brightly when the One Power is drawn through it.
Despite the fact that Callandor is second in strength only to the Choidan Kal (the twin giant sa'angreal in Cairhein and Trelmaking) it is flawed - it lacks a buffer that protects its wielder against all of the One Power they are drawing. Combined with the Dark One's taint on saidin, this makes it extremely dangerous to use.